function lazyload() {
    let temp1 = window.innerHeight || document.documentElement.clientHeight;
    let temp2 = document.body.scrollTop || document.documentElement.scrollTop;
    let maxshowHeight = temp1 + temp2;

    let imgSObj = document.querySelectorAll('img');
    // 遍历
    imgSObj.forEach(function (item, i) {

        if (item.offsetTop < maxshowHeight) {
            item.src = item.getAttribute('src-real');
        }
    })

}